Sports betting site Pinnacle Sports suspended wagers for a mixed doubles match at the Australian Open on Sunday after a suspicious large amount of money came in on the obscure match.

According to The New York Times, the match in question was the first-round mixed doubles game between the pairing of Czech Republic’s Andrea Hlavackova and Poland’s Lukasz Kubot against Spain’s David Marrero and Lara Arruabarrena.

Macro Blume, head of the sportsbook at Pinnacle Sports, told the news outlet that an unusual amount of bets came in for the Hlavackova and Kubot pair about 13 hours before the match started, indicating that the match might be fixed.

“We saw a small number of people placing a large amount of money.” Blume said, according to The New York Times.